Inflammation is a complex process that contributes to both tissue damage and repair. Lipopolysaccharide is a constituent of cell walls of gram- negative bacteria. It is a potent activator of humoral and cellular immunity and produces numerous changes in cell function, including enhancement of synthesis of the complement proteins factor B and C3 and the interleukins, IL-1 and IL-6. We have recognized a developmentally regulated response to LPS in both fibroblasts and peripheral blood monocytes. Fetal cells to not increase either synthesis of the proteins or levels of the mRNA. Neonatal cells (fibroblasts and monocytes) do respond to LPS stimulation with increased amounts of specific mRNAs for factor B and C3, but synthesis of the proteins is not initiated. The experiments presented in this application are designed to define the molecular basis of this developmental regulation in human cells. An animal model (mouse) is available for definition of the progression of the responsiveness through gestation and as the animal matures to adulthood. Protein synthesis will be examined by both two-dimensional gel electrophoresis to define the scope of the developmentally regulated differences in LPS responsiveness and by SDS-polyacrylamide gel electrophoresis to study specific proteins produced in these cells. Northern blot analysis will be used to study level regulation of changes in synthesis of specific proteins. Translation regulation of the LPS-induced mRNAs in neonatal cells will be studied using in vitro translation. Human newborns are particularly susceptible to E. coli and other gram negative infections. This susceptibility may be related tot he qualitative and quantitative decrease in response to LPS.